Dennis, I was with you until the end where you say: "Bottom line -- If you're going to build a linear do it right and go for a pair of 4-400's, single 4-1000A, 3-1000Z or one of the big Russian tubes I've seen on eBay recently."
Assuming one is going to build a linear, and so putting aside other issues such as linear vs plate modulation, why do you think it makes a difference what tube is used? Are you referring to running a linear at greater than legal limit?. 73, Mark W1EOF > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: Monday, January 30, 2006 5:01 PM > To: [EMAIL PROTECTED] > Cc: [email protected] > Subject: Re: [AMRadio] AM Transmitter Advice?? > > > Linears for AM -- here we go again for at least the third time in > the past 12 > months. > > Basic considerations: > > 1. Under carrier only conditions a correctly designed and > adjusted linear > amplifier will be operating at about 33% efficiency. So, with a > pair of 813's > the math works out to 125 watts of carrier, obviously not worth > the effort if > you're starting off with a 100 W carrier exciter. > > 2. The linear must be initially tuned up at the peak RF output > value which, > in turn, requires that the exciter (or some other source) must be > capable of > providing the input necessary to do this. Typically, his would > be 4 times > the carrier value but expect to hear a lot more on this from the > "asymmetrical > speech waveform" crowd. > > 3. "Real AM" can only come from a plate modulated class C PA in > the view of > certain members of this community. At the same time, big mod iron is > expensive and hard to find. Also, for a legal max rig the wall > plug efficiency of > "high level" and "linear" is not that much different in the final > analysis. > > Bottom line -- If you're going to build a linear do it right and go for a > pair of 4-400's, single 4-1000A, 3-1000Z or one of the big > Russian tubes I've > seen on eBay recently. I use my HB 3-1000Z amp on both SSB and > AM, BTW. Works > FB. > > Good luck with the project. > > Dennis D. W7QHO > Glendale, CA -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 267.14.22/239 - Release Date: 1/24/06
